In a precombustion-chamber type lean premixed gas internal combustion engine (hereinafter, referred to as a gas engine), to secure supply and safety of the fuel gas, a variety of devices, valves, and the like are provided.
Unpredictable leakage of the fuel gas may occur from the above devices, valves, and the like.
Fuel gas having leaked from the above devices, valves, and the like may flow to and accumulate in each of the gas engine, an exhaust channel, and the like.
If the gas engine is ignited and started under such a condition, the accumulating fuel gas undergoes abnormal combustion and damages the gas engine, the exhaust channel, and the like.
Patent Document 1 discloses a gas leakage checking device.
With reference to FIG. 5, a gas supply pipe 07 for supplying fuel gas to a gas burner 05 includes the first and second on-off valves 081, 082 disposed in series, and a proportional electromagnetic valve 09 disposed on the downstream side of the first and second on-off valves 081, 082. The above first and second on-off valves 081, 082 open when supplied with power, and close when not supplied with power due to a biasing force of a spring so as to shut off supply of fuel gas to the gas burner 05.
The proportional electromagnetic valve 09 adjusts the amount of fuel gas supply to the gas burner 05.
The gas burner 05 includes a spark electrode 010a that discharges sparks as an igniter 010 operates, and a thermocouple 011 serving as a flame-detection element for detecting flame of the gas burner 05.
Further, a controller 013 is provided, which controls operation of a fan motor 03a for driving a fan 03, the first and second on-off valves 081, 082, the proportional electromagnetic valve 09, the igniter 010, and the like.
To check gas leakage, the proportional electromagnetic valve 09 is maintained to be opened for a predetermined period of time or more when an operation switch is turned off, the rotation speed of the fan 03 is reduced to the lower-limit rotation speed within the normal operation range, and the igniter 010 is started.
Then, the first on-off valve 081 is opened, and the second on-off valve 082 is closed. Next, the first on-off valve 081 is closed, and the second on-off valve 082 is opened.
After elapse of a predetermined period of time, whether the gas burner 05 is put out is determined on the basis of the output of the thermocouple 011. As a result of the above series of control, check of the first on-off valve 081 is completed.
To check the second on-off valve 082, the first on-off valve 081 is closed, and the second on-off valve 082 is opened. Next, the first on-off valve 081 is opened, and the second on-off valve 082 is closed.
After elapse of a predetermined period of time, whether the gas burner 05 is put out is determined on the basis of the output of the thermocouple 011. As a result of the above series of control, check of the second on-off valve 082 is completed.
As a result of the two sets of control, check of the first and second on-off valves 081, 082 is completed.